Directive sound wave transmitter



0st. 4, 1966 B. DEROUET 3,277,432

DIRECTIVE SOUND WAVE TRANSMITTER Filed Jan. 8, 1964 FIGJ Fl W V1 TI TI T2 A 21 M 51 CONTROL CQNTRDL 1 o F H1! H1] 1 -0v/c DEVICE 22 52 2 IHI ma /H2 CONTROL .DEV/CE L CONTROL psv/cz PHASE RECEIVER AH/FTER United States atent 3,277,432 Patented Oct. 4, 1966 3,277,432 DIRECTIVE SOUND WAVE TRANSMITTER Brice Derouet, Paris, France, assignor to CSF-Compagnie Generale de Telegraphic Sans Fil, a corporation of France Filed Jan. 8, 1964, Ser. No. 336,513 Claims priority, application France, Jan. 11, 1963, 921,116 6 Claims. (Cl. 340-6) The present invention relates to sound Wave transmitters.

Directive sub-marine sound wave transmitters, made of arrays of vibrators, are known. The vibrators are generally excited in phase, so that the radiation diagram presents a directivity axis, perpendicular to the radiating array.

However, it is difficult to vary at will the directivity pattern, whether mechanically or electrically.

As a matter of fact, for reasons belonging to hydrodynamics, it may be difiicult to change the orientation of the directivity axis by adjustment of the transmitter position. As to the orientation by electrical means, it generally calls for phase shifter arrays difficult to realize.

It is an object of the invention to provide a directive sound wave transmitter comprising an array of elementary radiators, in which the direction of the directivity axis can be readily varied by purely electrical means.

A transmitter according to the invention, is characterized by the fact that each vibrator is an eleetroacoustic transducer which is controlled by two electrical circuits, fed by two alternating voltage sources, of the same frequency and phase shifted with respect to each other by a fixed amount. The phase of the waves respectively radiated by the transducer is then a function of the ratio of the amplitudes of the sound vibrations caused in the transducers by each of the circuits.

Means are provided to adjust the ratio of these amplitudes and hence vary the radiation pattern during transmission or reception.

The invention will be better understood from the following description and appended drawings in which:

FIG. 1 is an explanatory diagram;

FIG. 2 is a schematic diagram of a sound wave radiator according to the invention;

FIG. 3 is an explanatory diagram; and

FIG. 4 is a schematic diagram of a sound wave receiver according to the invention.

It is known that, to build a sound wave projector having a diagram having a predetermined directivity, alignments or arrays, as diagrammatically shown in FIG. 1, of equally spaced non directive vibrators can be used.

Angle formed by the maximal radiation direction with the normal to the array is given by the formula:

where is the operating wave length,

d is the distance between two consecutive vibrators, and

(p is the phase shift between the respective radiations of two consecutive sources.

In order to vary 6, (p must be varied.

The invention provides simple means for achieving this result.

FIG. 2, shows by way of example an array of four magnetostrictive vibrators 11, 12, 13 and 14. Of course, the vibrators may be of any other type serving the same purpose, for example, electrostrictive.

Each vibrator has two windings, fed by an alternating current source 2 of frequency f and angular frequency w.

Windings 21, 22, 23 and 24 are fed in series, a current 1 cos wt flowing through them. They receive one of the phases of source 2, which is then a two phase voltage source.

Windings 31, 32, 33 34 are fed in the same manner, and the current of amplitude I flowing therein, is advantageously in phase quadrature with current I They receive then the other phase of source 2. The current flowing in windings 31 to 34 can be written 1 sin wt.

It comes out, that the amplitude of the signal, transmitted by each vibrator, can be written:

J= I J 2 J k being a constant and 1m and n being the respective numbers of turns of two windings of vibrator j.

Also, phase to; being the phase of the signal transm1tted by vibrator 1', one can write:

The amplitude and phase of the signal transmitted by vibrator 11 are shown in FIG. 3.

It is seen that 1 /1 is a constant for all the vibrators and does not depend on the position number of the vibrator in the array.

To obtain an array effect, the vibrators being equidistant, phase qa must be a linear function of j, i.e. of the position number of the vibrator in the array.

Assuming, for example, that I /l is small, and that accordingly tan (PJ is substantially equal to one can write:

where a and b are constants.

In other words, ratio m /n must be a linear function of j in the case of this approximation.

Radiation direction 0, will then be controlled by acting on the ratio l /l by means of control devices 101 and 102. Then one will have:

21: g0, I1'bd sin 0 sin 6 depends on ratio l /l It should be noted that a variation of I and I has an influence upon the amplitude of each radiated signal, as can be seen referring to Formula 2. This results in a variation of the form of the radiation diagram. However, if variation of 0 are not too great, the diagram form will not much vary.

Of course, a transmitter according to the invention can be used at reception.

FIG. 4 shows an arrangement used for reception, the same reference numbers designating the same components as in FIG. 2. The arrangement comprises a receiver 3, directly connected to Windings 21 to 24, and through a phase shifter 4, providing a predetermined phase shift to windings 31 to 34. The two devices 111 and 112 control the amplitudes of the currents flowing towards the receiver, and hence regulate the directivity. The resultant phase shift in the receiver determines the direction of maximum sensitivity of the array of vibrators.

Of course, the invention is not limited to the embodiments shown and described. Thus is not necessary that the phase shift between currents supplied by the two windings of a vibrator should be 1r/2. The phase shift provided by the phase shifter 4 has only to be constant, since the steering of the beam is obtained by varying the amplitude ratio of said currents.

What is claimed is:

1. A directive sound wave radiator comprising an array of electro acoustic transducers, each of said transducers having a first and a second winding; said first and second windings being respectively connected in series, means for respectively applying to said windings two alternating voltages, said voltages being of the same frequency and phase shifted with respect to each other by a fixed amount, the respective ratios of the number of turns of said first and second windings of said transducers being a linear function of their position in said array and means for'varying the amplitudes of the currents in said windings.

2. A directive sound wave radiator comprising an array of magnetostrictive transducers, a first and a second electrical winding surrounding each of said transducers; said first and second windings being respectively connected in series means for respectively applying to said windings two alternating voltages, said voltages being of the same frequency and phase shifted with respect to each other" by 1r/2; the respective ratios of the number of turns of said first windings and the second windings of said transducers being a linear function of their position in said array and means for varying the amplitudes of the currents in said windings.

3. A directive sound wave radiator comprising an array of magnetostrictive transducers, a first and a second electrical winding surrounding each of said transducers, said first and second windings being respectively connected in series means for respectively applying to said windings two alternating voltages, said voltages being of the same frequency and phase shifted by a fixed amount with respect to each other, the respective ratios of the number of turns of said first windings and the second windings of said transducers being a linear function of the position of said transducers in said array, and means for varying the amplitudes of the currents in said windings.

4. A directive sound wave transmitter comprising an array of electro-acoustic transducers, a first and a second winding surrounding each of said transducers; said first windings and said second windings being respectively connected in series; means for respectively applying to said first and second windings alternating voltages phase shifted with respect to each other by a fixed amount, the respective ratios of the number of turns of said first and said second windings of said transducers being a linear function of their position in the array, and means for varying the amplitude of the current flowing through said windings.

5. A directive sound wave transmitter comprising an array of electro-acoustic transducer-s, a first and a second winding operating each of said transducers; a two phase voltage source having two first terminals and two second terminals for delivering a first and a second voltage phase shifted by 1r/2 with respect to each other; said first windings being connected in series between said first terminals, and said second windings being connected in series between said second terminals and the respective ratios of the number of turns of said first and said second windings of said transducers being a linear function of the position number of said transducers in the array; and means for varying the respective amplitudes of the current in said first and in said second windings.

6. A directive sound wave receiver comprising an array of electro-acoustic transducers; first and second windings wound on each of said transducers, the ratio of the respective numbers of turns of said first and said second windings of said transducers being a linear function of the position of said transducers in said array; a receiver having a first and a second input, a phase shifter and first amplitude controlling means in series between said first input and said first windings; second amplitude controlling means connected between said second input and said second windings and said phase shifter providing a predetermined phase shift.

References Cited by the Examiner UNITED STATES PATENTS 2,991,400 7/1961 Van Der Burgt 318-l 18 3,002,188 9/1961 Abbott 343-100 3,160,848 12/1964 Key et a1 34011 X CHESTER L. IUSTUS, Primary Examiner.

R. A. FARL-EY, Assistant Examiner. 

1. A DIRECTIVE SOUND WAVE RADIATOR COMPRISING AN ARRAY OF ELECTRO ACOUSTIC TRANSDUCERS, EACH OF SAID TRANSDUCERS HAVING A FIRST AND A SECOND WINDING; SAID FIRST AND SECOND WINDINGS BEING RESPECTIVELY CONNECTED IN SERIES, MEANS FOR RESPECTIVELY APPLYING TO SAID WINDINGS TWO ALTERNATING VOLTAGES, SAID VOLTAGES BEING OF THE SAME FREQUENCY AND PHASE SHITED WITH RESPECT TO EACH OTHER BY A FIXED AMOUNT, THE RESPECTIVE RATIOS OF THE NUMBER OF TURNS OF SAID FIRST AND SECOND WINDINGS OF SAID TRANSDUCERS BEING A LINEAR FUNCTION OF THEIR POSITION IN SAID ARRAY AND MEANS FOR VARYING THE AMPLITUDES OF THE CURRENTS IN SAID WINDINGS. 